The present invention relates to a disc drive apparatus that detects a type of a medium to be used.
Generally, in order to handle a disc appropriately, it is required that a disc drive apparatus detect a type of a medium to be used, as to type and size of the medium and as to whether the medium is a bare disc or accommodated in a cartridge.
With reference to a conventional disc drive apparatus (optical disc recording and reproducing device) shown in FIGS. 1 to 3, an explanation will be given on how to place a cartridge on a tray, a cartridge holding mechanism, and operations of loading and ejecting of a tray.
In FIG. 1, the reference numeral 201 denotes a body of an optical disc recording and reproducing device, 204 a tray, on which a cartridge and a bare optical disc are placed, and 100 a cartridge, in which an optical disc is accommodated.
A cartridge-placing surface 233 of the tray 204 is provided in the center thereof with two large and small recesses that are provided concentrically. A large-diameter recess defines a large-diameter disc-placing portion 231 and a small-diameter recess defines a small-diameter disc-placing portion 232, both recesses being prepared for use in accordance with an outside diameter of a disc placed in the optical disc recording and reproducing device 201.
In addition, the tray 204 is formed with a front wall 234, a left wall 235, and a right wall 236, which are slightly larger than outside dimension of the cartridge 100 and formed perpendicular to the cartridge-placing surface 233.
As shown in FIG. 2, a cartridge preloading member 237 is provided on an interior part of the tray 204 to be movable in a front/rear direction, and constructed to be held in a preloaded state on a front part of the tray 204.
Provided on a back surface of the tray 204 as shown in FIG. 3 is a rack gear 288 that engages with a final-stage drive gear of a loading gear system 281.
A loading motor 280 provided at the front part of a mechanical chassis 201a is switched in its rotation direction to enable the tray 204 to be loaded and ejected.
A traverse base 266 holds thereon a spindle motor 282 that holds and rotates a disc, an optical pickup 283 that reads and writes information from and onto a disc, a traverse motor 284 that moves the optical pickup 283 radially of a disc, and a lead screw 297.
A rear end of the traverse base 266 is turnably held on the mechanical chassis 201a by a torsion spring and a front end thereof is preloaded downward with a light load.
Two slit holes are provided right and left at the front end of the traverse base 266 to engage with a cam lever 285 that is inserted thereinto to turn about a rotating shaft 292 provided on a bottom surface of the mechanical chassis 201a. The traverse base 266 is vertically driven upon turning of the cam lever 285.
Provided on the traverse base 266 are two alignment pins 214 that engage with positioning holes of the cartridge 100 to keep a clearance between a disc held on the spindle motor 282 and the cartridge 100 to position the cartridge 100 where it does no contact with the disc.
A disc-state detection switch 215 is provided near the alignment pins 214. A plurality of detection switches mounted on a printed board are provided integrally with the traverse base 266 to distinguish a state of engagement with detection holes of the cartridge 100, thereby detecting a state of approval or denial of writing on a disc accommodated in the cartridge 100, front and back surfaces of a disc, and the recording capacity of a disc.
An upper base 228 as an upper lid is provided on the mechanical chassis 201a. Provided on the upper base 228 are a clamper 210 that fixes a disc to the spindle motor 282, clamp arms 212 that hold and make the clamper 210 vertically detachable from the spindle motor 282, and cartridge holding springs 229 that restrict vibrations of the cartridge 100 at the time of loading.
The cartridge 100 is fixed to the tray 204 by the downward biasing force of the cartridge holding springs 229. The biasing force of the cartridge holding springs 229 functions to urge the cartridge 100 against the tray 204 and urge the tray 204 against the mechanical chassis 201a from immediately after the beginning of loading to the completion of loading to eliminate looseness generated among the cartridge 100, the tray 204, and the mechanical chassis 201a, thus reducing vibrations and noise that are generated at the time of loading and rotation of a disc.
An operation of the optical disc recording and reproducing device 201 configured in the above manner will be described taking the case of reproducing a disc accommodated in the cartridge 100.
When placing the cartridge 100 on the tray 204 surrounded by the front wall 234, the left wall 235, and the right wall 236, placement of the cartridge 100 on the tray 204 is completed by sliding the cartridge 100 obliquely downward from forwardly upward of the tray 204 while causing a rear end of the cartridge 100 to push the cartridge preloading member 237 into the further inner part of the tray 204, and finally placing a front end of the cartridge 100 on the cartridge-placing surface 233 in a manner to bring the front end of the cartridge 100 into contact with an inner side of the front wall 234.
At this time, the front end of the cartridge 100 is pushed against the inner side of the front wall 234 by the cartridge preloading member 237 and the cartridge 100 is positioned relative to the tray 204 without looseness in back and forth and right to left directions.
The tray 204, on which the cartridge 100 is placed, is automatically loaded inside the optical disc recording and reproducing device 201 by a drive force of the loading motor 280.
Until loading of the tray 204 is completed, the spindle motor 282, the traverse motor 284, and the optical pickup 283, which are held on the traverse base 266, escape below a loading path of the tray 204 in order to avoid interference with the tray 204, the cartridge 100, and the disc.
Immediately before loading of the tray 204 is completed, a clamp-arm driving projection provided on the tray 204 pushes up one side of the clamp arm 212 that are turnably provided on the upper base 228 by hinges, and lowers the other side of the clamp arm 212, on which the clamper 210 is held. As a result, the clamper 210 is lowered to a position where a disc can be clamped.
When loading of the cartridge 100 placed on the tray 204 is completed after the clamper 210 is lowered, engagement between the tray 204 and the rack gear 288 is released, a drive force by the drive gear is cut off from the tray 204, and only the rack gear 288 is driven rearward relative to the tray 204. The force that drives the rack gear 288 rearward is transmitted to the cam lever 285 as torque of rotation, so that the traverse base 266 ascends along an inclination of the cam lever 285.
As the traverse base 266 ascends, the two alignment pins 214 provided integrally on the traverse base 266 are inserted into two positioning holes provided on the front part of the cartridge 100.
The cartridge 100 is caused to be positionally offset relative to the spindle motor 282 at the time of loading due to looseness between the tray 204 and the mechanical chassis 201a and looseness between the cartridge 100 and the tray 204. When a disc rotates while the cartridge 100 is offset relative to the spindle motor 282, noise is generated due to contact between an outer periphery of the disc and the inner wall of the cartridge 100. When there is a large positional offset, contact acts as resistance to release the clamped state of a disc which may damage the disc inside the cartridge 100.
The alignment pins 214 are inserted into the positioning holes of the cartridge 100 whereby the positional offset of the cartridge 100 relative to the spindle motor 282 is improved and an adequate clearance is ensured between the cartridge 100 and a disc.
Almost simultaneously with insertion of the alignment pins 214 into the positioning holes of the cartridge 100, the disc-state detection switch 215 is also inserted into the state detection hole of the cartridge 100.
Unlike the alignment pins 214, a large clearance is ensured between the state detection hole and the disc-state detection switch 215, so that the insertion is guaranteed with a margin with respect to detection of a state of the cartridge 100 even when the cartridge 100 is positionally offset.
With the insertion of the alignment pins 214 and the disc-state detection switch 215 into the cartridge 100, a center cone is inserted into a center hole of a disc accommodated in the cartridge 100 and the disc floats in a space inside the cartridge 100 while the traverse base 266 ascends.
As the disc floats, the clamper 210 standing by in a clamp position engages with the center cone and clamping of the disc is completed.
However, the conventional disc drive apparatus (optical disc recording and reproducing device) described above involves the following problem.
With respect to distinguishing the media, the switches arranged on the traverse distinguishes a cartridge immediately before the completion of loading. In addition, a 12-cm disc and an 8-cm disc are distinguished from each other after the spindle motor is rotated. Therefore, a preparatory time from insertion of a medium to the start is very long, casing such a problem that a desired scene can not be recorded.
Since there is not provided any means to detect a state of erroneous placement at the time of loading, there is the possibility that a disc falls off inside the drive at the time of loading and the disc cannot be taken out, if an 8-cm disc of small diameter is erroneously placed, offset from a predetermined position on a tray, which has a large opening at the center thereof.
Further, if a disc surface is clamped while the disc is erroneously placed, the disc surface may be damaged.